1. Field of the Invention
The present invention relates to ferrimagnetic materials, and more particularly to a stress stabilized ferrimagnetic material having improved stability of initial permeability throughout a relatively wide range of temperature and external pressure, and a method of manufacturing the stress stabilized ferrimagnetic material.
2. Description of Related Art
In the telecommunications field, the use of relatively high permeability ferrimagnetic materials, in the range of 5,000 to 20,000 is required in a number of systems. However, the operating environments for these telecommunication systems are subject to substantial variances. For example, the temperature surrounding the telecommunication system can range from −40° C. to 85° C.
The initial permeability (μi) of soft ferrite materials is sensitive to stress and temperature. In existing ferrimagnetic materials, a 40° C. temperature fluctuation can result in more than a 20% variance of initial permeability (μi). Such variance typically limits or precludes operation of the device incorporating the ferrimagnetic material. In addition, conventional ferrimagnetic materials have an initial permeability of less than 5,000 at −40° C. Specifically, it has been found that at low temperatures, initial permeability substantially decreases, which can adversely affect an operating characteristic of the ferrimagnetic component, which in turn can jeopardize the link in a surrounding communications network.
Further, manufacturing processes can subject the ferrimagnetic materials to external stresses, pressures or loading. These external pressures are often associated with operably installing the ferrimagnetic component in a system and can also adversely affect the initial permeability of the ferrimagnetic materials, and lead to unacceptable performance characteristics.
The influences from the external stress and temperature appear to be unavoidable in both packaging and operating environments. Also, smaller ferrimagnetic packages and incorporation of ferrimagnetics into connector modules force a minimization of the ferrimagnetic materials. Potting and molding techniques as well as flow and reflow soldering are now employed for operably packaging the ferrimagnetic materials. These packaging techniques can cause a significant drop in the initial permeability of the ferrimagnetic material. It is believed these drops in initial permeability can be as much as 60% of the engineered nominal value. Conventional ferrimagnetic materials do not work well under these conditions.
Therefore, the need exists for ferrimagnetic materials that can provide more consistent initial permeability across greater temperature ranges. The need also exists for ferrimagnetic materials that can maintain a initial permeability within acceptable ranges, while withstanding external pressures and loading, such as associated with manufacture and installation.